BRASILIA--Inmates rioting for better facilities in a Brazilian jail killed four fellow prisoners, decapitating two of them, and took two guards hostage, officials said Sunday.

Negotiations to resolve the standoff were to resume Monday, with 60 percent of the jail still under inmate control overnight, said Elson Faxina a state judicial spokesman.

Officials have cut water and electricity to the enclosure, Faxina added, saying police officers were guarding the prison to stop the riot from spreading.

"A group of prisoners took six inmates hostage; they killed four and have injured two. They also took hostage two guards," he explained.

"Their demands are about facilities; it is an older building and they want food brought in."

But Faxina said there may also be an element of the uprising linked to a fight between drug trafficking factions. "The fact that prisoners took hostages would reinforce that view," he said.

There were no numbers on how many inmates were involved in the uprising, but local media said around 77 prisoners were transferred because they were threatened by the rioters.

The uprising took place in the Cascavel state correctional center in the southern city of Parana that currently holds 1,140 prisoners, he said.

"A group of prisoners rebelled during breakfast and took two officers hostage. Then they beheaded two prisoners," a civilian police agent assigned to the jail, Miguel Llanela, told AFP earlier.

According to news portal G1, the two other prisoners were killed when they were thrown off the roof of the buildings.

"Negotiation are likely to be prolonged, and I hope things are resolved verbally without using physical force," an advocate for prison staff, Jairo Ferreira Filho, told a local radio station.

Meanwhile the prison workers union said in a statement that lack of funding meant there was no regular maintenance of the facility.

"The prisoners say the food is bad, there are no lawyers to work their trials, no basic hygiene materials, few correctional officers," the statement added.

"All these factors together are a tragedy waiting to happen."

In Brazil 548,000 people are currently in prison — and there is a need for 207,000 more spots to prevent overcrowding, according to Conectas, an organization specializing in inmate rights.

In May, inmates at a maximum-security prison in northeast Brazil took four guards and more than 100 visiting relatives hostage overnight, ultimately releasing them in a deal that saw the transfer of 16 inmates to other prisoners.